21

Challenge 21 - Write Your Own Sed

This challenge corresponds to the 21^st part of the Coding Challenges series by John Crickett https://codingchallenges.fyi/challenges/challenge-sed.

Description

The Sed tool is written in sed.ts. The tool is used to perform basic text transformations on an input stream (a file or input from stdin).

Usage

You can use ts-node to run the tool as follows:

# Substitute <this> for <that> everywhere <this> appears in the file <filename>
npx ts-node sed.ts s/<this>/<that>/g <filename>

# Print lines 2 to 4 from file <filename>
npx ts-node sed.ts -n "2,4p" <filename>

# Output only lines containing a specific pattern <pattern> from file <filename>
npx ts-node sed.ts -n /pattern/p <filename>

# Add another line after each line, i.e. double spacing a file.
npx ts-node sed.ts G <filename>

# Edit in-place: Substitute <this> for <that> everywhere <this> appears in the file <filename>
npx ts-node sed.ts -i 's/<this>/<that>/g' <filename>

The following options are supported:

• Character replacement
• Range of lines selection
• Output only lines containing a specific pattern
• Double spacing a file using option
• Strip trailing blank lines from a file
• Edit in-place

To use the tool in stdin mode, use the following command:

cat filename | npx ts-node sed.ts [option]

Run tests

To run the tests for the Sed tool, go to the root directory of this repository and run the following command:

npm test src/21/